IN THE FIELD 225 



kill plants in this way ? When plants or wood are put 

 into the fire, the coal burns and the ashes remain behind. 

 The substances which form the ashes and the large amount 

 of water present in all living plants are taken from the soil 

 by the roots. Water and soil are as necessary for plant life 

 as air. 



In order to examine this dark soil in which the plants 

 grow, we put a few handfuls of it into water and shake the 

 whole in this glass jar. The pebbles and gravel at once 

 sink to the bottom when we set the jar down, but the finer 

 soil is mixed with the water and gives it a muddy appear- 

 ance. After a while the finer soil also settles, and if we let 

 the jar stand long enough the water becomes again clear, 

 but on the surface float partly decayed plant remnants, 

 which are derived either from the plants that grew on the 

 soil or from manure. We can see through the glass that 

 the pebbles and the coarse gravel are at the bottom, and 

 that the finest mud is on top. Now we will put this soil 

 into a flower pot, pour water on it, and thoroughly stir the 

 whole. After the water is nearly clear I shall pour it off 

 carefully, take the cork out of the hole in the bottom of the 

 pot, and then I shall place the flower pot out in the sun, so 

 that the water may drain out and the soil be thoroughly 

 dried. You may observe the drying soil, and to-morrow or 

 the next day we shall study it again. 



41. Field and Garden Soil (Continuation). 



The soil which we placed out of doors is now so dry that 

 it has cracked and shrivelled. If we moisten small pieces 

 of it and then rub them between our fingers, we find that it 

 contains some clay, which makes it sticky, and we also feel 

 and see small grains of sand. But we wish to know what 

 gives the dark color to this soil, and Fred will tell us how 

 he found it out : " I placed a handful of dark soil on a large, 

 Q 



